Deadcode removal improvement

Deadcode removal in Obc :
- suppression of switch unused cases :

switch(true) {
  case false: ...
}

- activation with -deadcode option
This commit is contained in:
Gwenaël Delaval 2016-01-18 14:32:54 +01:00
parent 64b8c0592a
commit 2aed0f6537
2 changed files with 45 additions and 15 deletions

View file

@ -45,7 +45,8 @@ let compile_program p =
(*Dead code removal*)
let p = pass "Dead code removal"
(!do_mem_alloc || !do_linear_typing) Deadcode.program p pp in
(!do_mem_alloc || !do_linear_typing || !deadcode)
Deadcode.program p pp in
(*Control optimization*)
let p = pass "Control optimization" true Control.program p pp in

View file

@ -28,23 +28,52 @@
(***********************************************************************)
open Obc
open Obc_mapfold
let is_deadcode = function
| Aassgn (lhs, e) -> (* remove x=x equations *)
(match e.e_desc with
| Eextvalue w -> Obc_compare.compare_lhs_extvalue lhs w = 0
| _ -> false
)
| Acase (_, []) -> true
| Afor(_, _, _, { b_body = [] }) -> true
| _ -> false
open Types
open Initial
let act funs act_list a =
let a, _ = Obc_mapfold.act funs [] a in
if is_deadcode a then
a, act_list
else
a, a::act_list
match a with
| Aassgn (lhs, e) -> (* remove x=x equations *)
(match e.e_desc with
| Eextvalue w when (Obc_compare.compare_lhs_extvalue lhs w = 0)
-> a, act_list (* removal of action *)
| _ -> a, a :: act_list
)
| Acase (_, []) -> a, act_list (* removal *)
| Acase ({e_desc =
Eextvalue(
{w_desc = Wconst ({se_desc = Sbool b})}
)
},
c_b_l) ->
let pb = if b then ptrue else pfalse in
let c_b_l = List.filter (fun (c,b) -> c = pb) c_b_l in
begin
match c_b_l with
[c,b] ->
let a = Ablock b in
a, a :: act_list
| [] -> a, act_list
| _ -> assert false (* More than one case after filter *)
end
| Acase ({e_desc =
Eextvalue(
{w_desc = Wconst ({se_desc = Sconstructor ce})}
)
},
c_b_l) ->
let c_b_l = List.filter (fun (c,b) -> c = ce) c_b_l in
begin
match c_b_l with
[c,b] ->
let a = Ablock b in
a, a :: act_list
| [] -> a, act_list
| _ -> assert false (* More than one case after filter *)
end
| Afor(_, _, _, { b_body = [] }) -> a, act_list (* removal *)
| _ -> a, a :: act_list
let block funs acc b =
let _, act_list = Obc_mapfold.block funs [] b in